From b3077fb9ac2668fde05478fa0ef6197fecda87b6 Mon Sep 17 00:00:00 2001
From: Luke Wren <wren6991@gmail.com>
Date: Sat, 5 Sep 2015 01:14:45 +0100
Subject: [PATCH] Add SMI driver

Signed-off-by: Luke Wren <wren6991@gmail.com>

MISC: bcm2835: smi: use clock manager and fix reload issues

Use clock manager instead of self-made clockmanager.

Also fix some error paths that showd up during development
(especially missing release of dma resources on rmmod)

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>

bcm2835_smi: re-add dereference to fix DMA transfers

bcm2835_smi_dev: Fix handling of word-odd lengths

The read and write functions did not use the correct pointer offset
when dealing with an odd number of bytes after a DMA transfer. Also,
only handle the remaining odd bytes if the DMA transfer completed
successfully.

Submitted-by: @madimario (GitHub)
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

misc: bcm2835_smi: Use proper enum types for dma_{,un}map_single()

Clang warns:

  drivers/misc/bcm2835_smi.c:692:4: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                          DMA_MEM_TO_DEV);
                          ^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:406:66: note: expanded from macro 'dma_map_single'
  #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
                                     ~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:705:35: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                          (inst->dev, phy_addr, n_bytes, DMA_MEM_TO_DEV);
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:407:70: note: expanded from macro 'dma_unmap_single'
  #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
                                       ~~~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:751:12: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                                                       DMA_DEV_TO_MEM);
                                                       ^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:406:66: note: expanded from macro 'dma_map_single'
  #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
                                     ~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:761:50: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                  dma_unmap_single(inst->dev, phy_addr, n_bytes, DMA_DEV_TO_MEM);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:407:70: note: expanded from macro 'dma_unmap_single'
  #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
                                       ~~~~~~~~~~~~~~~~~~~~~~          ^
  4 warnings generated.

Use the proper enumerated type to clear up the warning. There is not
actually a bug here because the enumerated types have the same integer
value:

DMA_MEM_TO_DEV = DMA_TO_DEVICE = 1
DMA_DEV_TO_MEM = DMA_FROM_DEVICE = 2

Fixes: 93254d0f7bc8 ("Add SMI driver")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 .../bindings/misc/brcm,bcm2835-smi-dev.txt    |  17 +
 .../bindings/misc/brcm,bcm2835-smi.txt        |  48 +
 drivers/char/broadcom/Kconfig                 |   9 +
 drivers/char/broadcom/Makefile                |   1 +
 drivers/char/broadcom/bcm2835_smi_dev.c       | 409 ++++++++
 drivers/misc/Kconfig                          |   8 +
 drivers/misc/Makefile                         |   1 +
 drivers/misc/bcm2835_smi.c                    | 955 ++++++++++++++++++
 include/linux/broadcom/bcm2835_smi.h          | 391 +++++++
 9 files changed, 1839 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/brcm,bcm2835-smi-dev.txt
 create mode 100644 Documentation/devicetree/bindings/misc/brcm,bcm2835-smi.txt
 create mode 100644 drivers/char/broadcom/bcm2835_smi_dev.c
 create mode 100644 drivers/misc/bcm2835_smi.c
 create mode 100644 include/linux/broadcom/bcm2835_smi.h

--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/brcm,bcm2835-smi-dev.txt
@@ -0,0 +1,17 @@
+* Broadcom BCM2835 SMI character device driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+This driver adds a character device which provides a user-space interface to
+an instance of the SMI driver.
+
+Required properties:
+- compatible: "brcm,bcm2835-smi-dev"
+- smi_handle: a phandle to the smi node.
+
+Optional properties:
+- None.
+
+
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/brcm,bcm2835-smi.txt
@@ -0,0 +1,48 @@
+* Broadcom BCM2835 SMI driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+Required properties:
+- compatible: "brcm,bcm2835-smi"
+- reg: Should contain location and length of SMI registers and SMI clkman regs
+- interrupts: *the* SMI interrupt.
+- pinctrl-names: should be "default".
+- pinctrl-0: the phandle of the gpio pin node.
+- brcm,smi-clock-source: the clock source for clkman
+- brcm,smi-clock-divisor: the integer clock divisor for clkman
+- dmas: the dma controller phandle and the DREQ number (4 on a 2835)
+- dma-names: the name used by the driver to request its channel.
+  Should be "rx-tx".
+
+Optional properties:
+- None.
+
+Examples:
+
+8 data pin configuration:
+
+smi: smi@7e600000 {
+	compatible = "brcm,bcm2835-smi";
+	reg = <0x7e600000 0x44>, <0x7e1010b0 0x8>;
+	interrupts = <2 16>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&smi_pins>;
+	brcm,smi-clock-source = <6>;
+	brcm,smi-clock-divisor = <4>;
+	dmas = <&dma 4>;
+	dma-names = "rx-tx";
+
+	status = "okay";
+};
+
+smi_pins: smi_pins {
+	brcm,pins = <2 3 4 5 6 7 8 9 10 11 12 13 14 15>;
+	/* Alt 1: SMI */
+	brcm,function = <5 5 5 5 5 5 5 5 5 5 5 5 5 5>;
+	/* /CS, /WE and /OE are pulled high, as they are
+	   generally active low signals */
+	brcm,pull = <2 2 2 2 2 2 0 0 0 0 0 0 0 0>;
+};
+
--- a/drivers/char/broadcom/Kconfig
+++ b/drivers/char/broadcom/Kconfig
@@ -24,3 +24,12 @@ config BCM2835_DEVGPIOMEM
 		Provides users with root-free access to the GPIO registers
 		on the 2835. Calling mmap(/dev/gpiomem) will map the GPIO
 		register page to the user's pointer.
+
+config BCM2835_SMI_DEV
+	tristate "Character device driver for BCM2835 Secondary Memory Interface"
+	depends on BCM2835_SMI
+	default m
+	help
+		This driver provides a character device interface (ioctl + read/write) to
+		Broadcom's Secondary Memory interface. The low-level functionality is provided
+		by the SMI driver itself.
--- a/drivers/char/broadcom/Makefile
+++ b/drivers/char/broadcom/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_BCM2708_VCMEM)	+= vc_mem.o
 obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o
+obj-$(CONFIG_BCM2835_SMI_DEV)	+= bcm2835_smi_dev.o
--- /dev/null
+++ b/drivers/char/broadcom/bcm2835_smi_dev.c
@@ -0,0 +1,409 @@
+/**
+ * Character device driver for Broadcom Secondary Memory Interface
+ *
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+
+#include <linux/broadcom/bcm2835_smi.h>
+
+#define DEVICE_NAME "bcm2835-smi-dev"
+#define DRIVER_NAME "smi-dev-bcm2835"
+#define DEVICE_MINOR 0
+
+static struct cdev bcm2835_smi_cdev;
+static dev_t bcm2835_smi_devid;
+static struct class *bcm2835_smi_class;
+static struct device *bcm2835_smi_dev;
+
+struct bcm2835_smi_dev_instance {
+	struct device *dev;
+};
+
+static struct bcm2835_smi_instance *smi_inst;
+static struct bcm2835_smi_dev_instance *inst;
+
+static const char *const ioctl_names[] = {
+	"READ_SETTINGS",
+	"WRITE_SETTINGS",
+	"ADDRESS"
+};
+
+/****************************************************************************
+*
+*   SMI chardev file ops
+*
+***************************************************************************/
+static long
+bcm2835_smi_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	long ret = 0;
+
+	dev_info(inst->dev, "serving ioctl...");
+
+	switch (cmd) {
+	case BCM2835_SMI_IOC_GET_SETTINGS:{
+		struct smi_settings *settings;
+
+		dev_info(inst->dev, "Reading SMI settings to user.");
+		settings = bcm2835_smi_get_settings_from_regs(smi_inst);
+		if (copy_to_user((void *)arg, settings,
+				 sizeof(struct smi_settings)))
+			dev_err(inst->dev, "settings copy failed.");
+		break;
+	}
+	case BCM2835_SMI_IOC_WRITE_SETTINGS:{
+		struct smi_settings *settings;
+
+		dev_info(inst->dev, "Setting user's SMI settings.");
+		settings = bcm2835_smi_get_settings_from_regs(smi_inst);
+		if (copy_from_user(settings, (void *)arg,
+				   sizeof(struct smi_settings)))
+			dev_err(inst->dev, "settings copy failed.");
+		else
+			bcm2835_smi_set_regs_from_settings(smi_inst);
+		break;
+	}
+	case BCM2835_SMI_IOC_ADDRESS:
+		dev_info(inst->dev, "SMI address set: 0x%02x", (int)arg);
+		bcm2835_smi_set_address(smi_inst, arg);
+		break;
+	default:
+		dev_err(inst->dev, "invalid ioctl cmd: %d", cmd);
+		ret = -ENOTTY;
+		break;
+	}
+
+	return ret;
+}
+
+static int bcm2835_smi_open(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+
+	dev_dbg(inst->dev, "SMI device opened.");
+
+	if (dev != DEVICE_MINOR) {
+		dev_err(inst->dev,
+			"bcm2835_smi_release: Unknown minor device: %d",
+			dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int bcm2835_smi_release(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode);
+
+	if (dev != DEVICE_MINOR) {
+		dev_err(inst->dev,
+			"bcm2835_smi_release: Unknown minor device %d", dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static ssize_t dma_bounce_user(
+	enum dma_transfer_direction dma_dir,
+	char __user *user_ptr,
+	size_t count,
+	struct bcm2835_smi_bounce_info *bounce)
+{
+	int chunk_size;
+	int chunk_no = 0;
+	int count_left = count;
+
+	while (count_left) {
+		int rv;
+		void *buf;
+
+		/* Wait for current chunk to complete: */
+		if (down_timeout(&bounce->callback_sem,
+			msecs_to_jiffies(1000))) {
+			dev_err(inst->dev, "DMA bounce timed out");
+			count -= (count_left);
+			break;
+		}
+
+		if (bounce->callback_sem.count >= DMA_BOUNCE_BUFFER_COUNT - 1)
+			dev_err(inst->dev, "WARNING: Ring buffer overflow");
+		chunk_size = count_left > DMA_BOUNCE_BUFFER_SIZE ?
+			DMA_BOUNCE_BUFFER_SIZE : count_left;
+		buf = bounce->buffer[chunk_no % DMA_BOUNCE_BUFFER_COUNT];
+		if (dma_dir == DMA_DEV_TO_MEM)
+			rv = copy_to_user(user_ptr, buf, chunk_size);
+		else
+			rv = copy_from_user(buf, user_ptr, chunk_size);
+		if (rv)
+			dev_err(inst->dev, "copy_*_user() failed!: %d", rv);
+		user_ptr += chunk_size;
+		count_left -= chunk_size;
+		chunk_no++;
+	}
+	return count;
+}
+
+static ssize_t
+bcm2835_read_file(struct file *f, char __user *user_ptr,
+		  size_t count, loff_t *offs)
+{
+	int odd_bytes;
+	size_t count_check;
+
+	dev_dbg(inst->dev, "User reading %zu bytes from SMI.", count);
+	/* We don't want to DMA a number of bytes % 4 != 0 (32 bit FIFO) */
+	if (count > DMA_THRESHOLD_BYTES)
+		odd_bytes = count & 0x3;
+	else
+		odd_bytes = count;
+	count -= odd_bytes;
+	count_check = count;
+	if (count) {
+		struct bcm2835_smi_bounce_info *bounce;
+
+		count = bcm2835_smi_user_dma(smi_inst,
+			DMA_DEV_TO_MEM, user_ptr, count,
+			&bounce);
+		if (count)
+			count = dma_bounce_user(DMA_DEV_TO_MEM, user_ptr,
+				count, bounce);
+	}
+	if (odd_bytes && (count == count_check)) {
+		/* Read from FIFO directly if not using DMA */
+		uint8_t buf[DMA_THRESHOLD_BYTES];
+		unsigned long bytes_not_transferred;
+
+		bcm2835_smi_read_buf(smi_inst, buf, odd_bytes);
+		bytes_not_transferred = copy_to_user(user_ptr + count, buf, odd_bytes);
+		if (bytes_not_transferred)
+			dev_err(inst->dev, "copy_to_user() failed.");
+		count += odd_bytes - bytes_not_transferred;
+	}
+	return count;
+}
+
+static ssize_t
+bcm2835_write_file(struct file *f, const char __user *user_ptr,
+		   size_t count, loff_t *offs)
+{
+	int odd_bytes;
+	size_t count_check;
+
+	dev_dbg(inst->dev, "User writing %zu bytes to SMI.", count);
+	if (count > DMA_THRESHOLD_BYTES)
+		odd_bytes = count & 0x3;
+	else
+		odd_bytes = count;
+	count -= odd_bytes;
+	count_check = count;
+	if (count) {
+		struct bcm2835_smi_bounce_info *bounce;
+
+		count = bcm2835_smi_user_dma(smi_inst,
+			DMA_MEM_TO_DEV, (char __user *)user_ptr, count,
+			&bounce);
+		if (count)
+			count = dma_bounce_user(DMA_MEM_TO_DEV,
+				(char __user *)user_ptr,
+				count, bounce);
+	}
+	if (odd_bytes && (count == count_check)) {
+		uint8_t buf[DMA_THRESHOLD_BYTES];
+		unsigned long bytes_not_transferred;
+
+		bytes_not_transferred = copy_from_user(buf, user_ptr + count, odd_bytes);
+		if (bytes_not_transferred)
+			dev_err(inst->dev, "copy_from_user() failed.");
+		else
+			bcm2835_smi_write_buf(smi_inst, buf, odd_bytes);
+		count += odd_bytes - bytes_not_transferred;
+	}
+	return count;
+}
+
+static const struct file_operations
+bcm2835_smi_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = bcm2835_smi_ioctl,
+	.open = bcm2835_smi_open,
+	.release = bcm2835_smi_release,
+	.read = bcm2835_read_file,
+	.write = bcm2835_write_file,
+};
+
+
+/****************************************************************************
+*
+*   bcm2835_smi_probe - called when the driver is loaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_dev_probe(struct platform_device *pdev)
+{
+	int err;
+	void *ptr_err;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node, *smi_node;
+
+	if (!node) {
+		dev_err(dev, "No device tree node supplied!");
+		return -EINVAL;
+	}
+
+	smi_node = of_parse_phandle(node, "smi_handle", 0);
+
+	if (!smi_node) {
+		dev_err(dev, "No such property: smi_handle");
+		return -ENXIO;
+	}
+
+	smi_inst = bcm2835_smi_get(smi_node);
+
+	if (!smi_inst)
+		return -EPROBE_DEFER;
+
+	/* Allocate buffers and instance data */
+
+	inst = devm_kzalloc(dev, sizeof(*inst), GFP_KERNEL);
+
+	if (!inst)
+		return -ENOMEM;
+
+	inst->dev = dev;
+
+	/* Create character device entries */
+
+	err = alloc_chrdev_region(&bcm2835_smi_devid,
+				  DEVICE_MINOR, 1, DEVICE_NAME);
+	if (err != 0) {
+		dev_err(inst->dev, "unable to allocate device number");
+		return -ENOMEM;
+	}
+	cdev_init(&bcm2835_smi_cdev, &bcm2835_smi_fops);
+	bcm2835_smi_cdev.owner = THIS_MODULE;
+	err = cdev_add(&bcm2835_smi_cdev, bcm2835_smi_devid, 1);
+	if (err != 0) {
+		dev_err(inst->dev, "unable to register device");
+		err = -ENOMEM;
+		goto failed_cdev_add;
+	}
+
+	/* Create sysfs entries */
+
+	bcm2835_smi_class = class_create(THIS_MODULE, DEVICE_NAME);
+	ptr_err = bcm2835_smi_class;
+	if (IS_ERR(ptr_err))
+		goto failed_class_create;
+
+	bcm2835_smi_dev = device_create(bcm2835_smi_class, NULL,
+					bcm2835_smi_devid, NULL,
+					"smi");
+	ptr_err = bcm2835_smi_dev;
+	if (IS_ERR(ptr_err))
+		goto failed_device_create;
+
+	dev_info(inst->dev, "initialised");
+
+	return 0;
+
+failed_device_create:
+	class_destroy(bcm2835_smi_class);
+failed_class_create:
+	cdev_del(&bcm2835_smi_cdev);
+	err = PTR_ERR(ptr_err);
+failed_cdev_add:
+	unregister_chrdev_region(bcm2835_smi_devid, 1);
+	dev_err(dev, "could not load bcm2835_smi_dev");
+	return err;
+}
+
+/****************************************************************************
+*
+*   bcm2835_smi_remove - called when the driver is unloaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_dev_remove(struct platform_device *pdev)
+{
+	device_destroy(bcm2835_smi_class, bcm2835_smi_devid);
+	class_destroy(bcm2835_smi_class);
+	cdev_del(&bcm2835_smi_cdev);
+	unregister_chrdev_region(bcm2835_smi_devid, 1);
+
+	dev_info(inst->dev, "SMI character dev removed - OK");
+	return 0;
+}
+
+/****************************************************************************
+*
+*   Register the driver with device tree
+*
+***************************************************************************/
+
+static const struct of_device_id bcm2835_smi_dev_of_match[] = {
+	{.compatible = "brcm,bcm2835-smi-dev",},
+	{ /* sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, bcm2835_smi_dev_of_match);
+
+static struct platform_driver bcm2835_smi_dev_driver = {
+	.probe = bcm2835_smi_dev_probe,
+	.remove = bcm2835_smi_dev_remove,
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+		   .of_match_table = bcm2835_smi_dev_of_match,
+		   },
+};
+
+module_platform_driver(bcm2835_smi_dev_driver);
+
+MODULE_ALIAS("platform:smi-dev-bcm2835");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION(
+	"Character device driver for BCM2835's secondary memory interface");
+MODULE_AUTHOR("Luke Wren <luke@raspberrypi.org>");
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -9,6 +9,14 @@ config SENSORS_LIS3LV02D
 	tristate
 	depends on INPUT
 
+config BCM2835_SMI
+	tristate "Broadcom 283x Secondary Memory Interface driver"
+	depends on ARCH_BCM2835
+	default m
+	help
+		Driver for enabling and using Broadcom's Secondary/Slow Memory Interface.
+		Appears as /dev/bcm2835_smi. For ioctl interface see drivers/misc/bcm2835_smi.h
+
 config AD525X_DPOT
 	tristate "Analog Devices Digital Potentiometers"
 	depends on (I2C || SPI) && SYSFS
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_AD525X_DPOT)	+= ad525x_dpot
 obj-$(CONFIG_AD525X_DPOT_I2C)	+= ad525x_dpot-i2c.o
 obj-$(CONFIG_AD525X_DPOT_SPI)	+= ad525x_dpot-spi.o
 obj-$(CONFIG_ATMEL_SSC)		+= atmel-ssc.o
+obj-$(CONFIG_BCM2835_SMI)	+= bcm2835_smi.o
 obj-$(CONFIG_DUMMY_IRQ)		+= dummy-irq.o
 obj-$(CONFIG_ICS932S401)	+= ics932s401.o
 obj-$(CONFIG_LKDTM)		+= lkdtm/
--- /dev/null
+++ b/drivers/misc/bcm2835_smi.c
@@ -0,0 +1,955 @@
+/**
+ * Broadcom Secondary Memory Interface driver
+ *
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/clk.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/semaphore.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+
+#define BCM2835_SMI_IMPLEMENTATION
+#include <linux/broadcom/bcm2835_smi.h>
+
+#define DRIVER_NAME "smi-bcm2835"
+
+#define N_PAGES_FROM_BYTES(n) ((n + PAGE_SIZE-1) / PAGE_SIZE)
+
+#define DMA_WRITE_TO_MEM true
+#define DMA_READ_FROM_MEM false
+
+struct bcm2835_smi_instance {
+	struct device *dev;
+	struct smi_settings settings;
+	__iomem void *smi_regs_ptr;
+	dma_addr_t smi_regs_busaddr;
+
+	struct dma_chan *dma_chan;
+	struct dma_slave_config dma_config;
+
+	struct bcm2835_smi_bounce_info bounce;
+
+	struct scatterlist buffer_sgl;
+
+	struct clk *clk;
+
+	/* Sometimes we are called into in an atomic context (e.g. by
+	   JFFS2 + MTD) so we can't use a mutex */
+	spinlock_t transaction_lock;
+};
+
+/****************************************************************************
+*
+*   SMI peripheral setup
+*
+***************************************************************************/
+
+static inline void write_smi_reg(struct bcm2835_smi_instance *inst,
+	u32 val, unsigned reg)
+{
+	writel(val, inst->smi_regs_ptr + reg);
+}
+
+static inline u32 read_smi_reg(struct bcm2835_smi_instance *inst, unsigned reg)
+{
+	return readl(inst->smi_regs_ptr + reg);
+}
+
+/* Token-paste macro for e.g SMIDSR_RSTROBE ->  value of SMIDSR_RSTROBE_MASK */
+#define _CONCAT(x, y) x##y
+#define CONCAT(x, y) _CONCAT(x, y)
+
+#define SET_BIT_FIELD(dest, field, bits) ((dest) = \
+	((dest) & ~CONCAT(field, _MASK)) | (((bits) << CONCAT(field, _OFFS))& \
+	 CONCAT(field, _MASK)))
+#define GET_BIT_FIELD(src, field) (((src) & \
+	CONCAT(field, _MASK)) >> CONCAT(field, _OFFS))
+
+static void smi_dump_context_labelled(struct bcm2835_smi_instance *inst,
+	const char *label)
+{
+	dev_err(inst->dev, "SMI context dump: %s", label);
+	dev_err(inst->dev, "SMICS:  0x%08x", read_smi_reg(inst, SMICS));
+	dev_err(inst->dev, "SMIL:   0x%08x", read_smi_reg(inst, SMIL));
+	dev_err(inst->dev, "SMIDSR: 0x%08x", read_smi_reg(inst, SMIDSR0));
+	dev_err(inst->dev, "SMIDSW: 0x%08x", read_smi_reg(inst, SMIDSW0));
+	dev_err(inst->dev, "SMIDC:  0x%08x", read_smi_reg(inst, SMIDC));
+	dev_err(inst->dev, "SMIFD:  0x%08x", read_smi_reg(inst, SMIFD));
+	dev_err(inst->dev, " ");
+}
+
+static inline void smi_dump_context(struct bcm2835_smi_instance *inst)
+{
+	smi_dump_context_labelled(inst, "");
+}
+
+static void smi_get_default_settings(struct bcm2835_smi_instance *inst)
+{
+	struct smi_settings *settings = &inst->settings;
+
+	settings->data_width = SMI_WIDTH_16BIT;
+	settings->pack_data = true;
+
+	settings->read_setup_time = 1;
+	settings->read_hold_time = 1;
+	settings->read_pace_time = 1;
+	settings->read_strobe_time = 3;
+
+	settings->write_setup_time = settings->read_setup_time;
+	settings->write_hold_time = settings->read_hold_time;
+	settings->write_pace_time = settings->read_pace_time;
+	settings->write_strobe_time = settings->read_strobe_time;
+
+	settings->dma_enable = true;
+	settings->dma_passthrough_enable = false;
+	settings->dma_read_thresh = 0x01;
+	settings->dma_write_thresh = 0x3f;
+	settings->dma_panic_read_thresh = 0x20;
+	settings->dma_panic_write_thresh = 0x20;
+}
+
+void bcm2835_smi_set_regs_from_settings(struct bcm2835_smi_instance *inst)
+{
+	struct smi_settings *settings = &inst->settings;
+	int smidsr_temp = 0, smidsw_temp = 0, smics_temp,
+	    smidcs_temp, smidc_temp = 0;
+
+	spin_lock(&inst->transaction_lock);
+
+	/* temporarily disable the peripheral: */
+	smics_temp = read_smi_reg(inst, SMICS);
+	write_smi_reg(inst, 0, SMICS);
+	smidcs_temp = read_smi_reg(inst, SMIDCS);
+	write_smi_reg(inst, 0, SMIDCS);
+
+	if (settings->pack_data)
+		smics_temp |= SMICS_PXLDAT;
+	else
+		smics_temp &= ~SMICS_PXLDAT;
+
+	SET_BIT_FIELD(smidsr_temp, SMIDSR_RWIDTH, settings->data_width);
+	SET_BIT_FIELD(smidsr_temp, SMIDSR_RSETUP, settings->read_setup_time);
+	SET_BIT_FIELD(smidsr_temp, SMIDSR_RHOLD, settings->read_hold_time);
+	SET_BIT_FIELD(smidsr_temp, SMIDSR_RPACE, settings->read_pace_time);
+	SET_BIT_FIELD(smidsr_temp, SMIDSR_RSTROBE, settings->read_strobe_time);
+	write_smi_reg(inst, smidsr_temp, SMIDSR0);
+
+	SET_BIT_FIELD(smidsw_temp, SMIDSW_WWIDTH, settings->data_width);
+	if (settings->data_width == SMI_WIDTH_8BIT)
+		smidsw_temp |= SMIDSW_WSWAP;
+	else
+		smidsw_temp &= ~SMIDSW_WSWAP;
+	SET_BIT_FIELD(smidsw_temp, SMIDSW_WSETUP, settings->write_setup_time);
+	SET_BIT_FIELD(smidsw_temp, SMIDSW_WHOLD, settings->write_hold_time);
+	SET_BIT_FIELD(smidsw_temp, SMIDSW_WPACE, settings->write_pace_time);
+	SET_BIT_FIELD(smidsw_temp, SMIDSW_WSTROBE,
+			settings->write_strobe_time);
+	write_smi_reg(inst, smidsw_temp, SMIDSW0);
+
+	SET_BIT_FIELD(smidc_temp, SMIDC_REQR, settings->dma_read_thresh);
+	SET_BIT_FIELD(smidc_temp, SMIDC_REQW, settings->dma_write_thresh);
+	SET_BIT_FIELD(smidc_temp, SMIDC_PANICR,
+		      settings->dma_panic_read_thresh);
+	SET_BIT_FIELD(smidc_temp, SMIDC_PANICW,
+		      settings->dma_panic_write_thresh);
+	if (settings->dma_passthrough_enable) {
+		smidc_temp |= SMIDC_DMAP;
+		smidsr_temp |= SMIDSR_RDREQ;
+		write_smi_reg(inst, smidsr_temp, SMIDSR0);
+		smidsw_temp |= SMIDSW_WDREQ;
+		write_smi_reg(inst, smidsw_temp, SMIDSW0);
+	} else
+		smidc_temp &= ~SMIDC_DMAP;
+	if (settings->dma_enable)
+		smidc_temp |= SMIDC_DMAEN;
+	else
+		smidc_temp &= ~SMIDC_DMAEN;
+
+	write_smi_reg(inst, smidc_temp, SMIDC);
+
+	/* re-enable (if was previously enabled) */
+	write_smi_reg(inst, smics_temp, SMICS);
+	write_smi_reg(inst, smidcs_temp, SMIDCS);
+
+	spin_unlock(&inst->transaction_lock);
+}
+EXPORT_SYMBOL(bcm2835_smi_set_regs_from_settings);
+
+struct smi_settings *bcm2835_smi_get_settings_from_regs
+	(struct bcm2835_smi_instance *inst)
+{
+	struct smi_settings *settings = &inst->settings;
+	int smidsr, smidsw, smidc;
+
+	spin_lock(&inst->transaction_lock);
+
+	smidsr = read_smi_reg(inst, SMIDSR0);
+	smidsw = read_smi_reg(inst, SMIDSW0);
+	smidc = read_smi_reg(inst, SMIDC);
+
+	settings->pack_data = (read_smi_reg(inst, SMICS) & SMICS_PXLDAT) ?
+	    true : false;
+
+	settings->data_width = GET_BIT_FIELD(smidsr, SMIDSR_RWIDTH);
+	settings->read_setup_time = GET_BIT_FIELD(smidsr, SMIDSR_RSETUP);
+	settings->read_hold_time = GET_BIT_FIELD(smidsr, SMIDSR_RHOLD);
+	settings->read_pace_time = GET_BIT_FIELD(smidsr, SMIDSR_RPACE);
+	settings->read_strobe_time = GET_BIT_FIELD(smidsr, SMIDSR_RSTROBE);
+
+	settings->write_setup_time = GET_BIT_FIELD(smidsw, SMIDSW_WSETUP);
+	settings->write_hold_time = GET_BIT_FIELD(smidsw, SMIDSW_WHOLD);
+	settings->write_pace_time = GET_BIT_FIELD(smidsw, SMIDSW_WPACE);
+	settings->write_strobe_time = GET_BIT_FIELD(smidsw, SMIDSW_WSTROBE);
+
+	settings->dma_read_thresh = GET_BIT_FIELD(smidc, SMIDC_REQR);
+	settings->dma_write_thresh = GET_BIT_FIELD(smidc, SMIDC_REQW);
+	settings->dma_panic_read_thresh = GET_BIT_FIELD(smidc, SMIDC_PANICR);
+	settings->dma_panic_write_thresh = GET_BIT_FIELD(smidc, SMIDC_PANICW);
+	settings->dma_passthrough_enable = (smidc & SMIDC_DMAP) ? true : false;
+	settings->dma_enable = (smidc & SMIDC_DMAEN) ? true : false;
+
+	spin_unlock(&inst->transaction_lock);
+
+	return settings;
+}
+EXPORT_SYMBOL(bcm2835_smi_get_settings_from_regs);
+
+static inline void smi_set_address(struct bcm2835_smi_instance *inst,
+	unsigned int address)
+{
+	int smia_temp = 0, smida_temp = 0;
+
+	SET_BIT_FIELD(smia_temp, SMIA_ADDR, address);
+	SET_BIT_FIELD(smida_temp, SMIDA_ADDR, address);
+
+	/* Write to both address registers - user doesn't care whether we're
+	   doing programmed or direct transfers. */
+	write_smi_reg(inst, smia_temp, SMIA);
+	write_smi_reg(inst, smida_temp, SMIDA);
+}
+
+static void smi_setup_regs(struct bcm2835_smi_instance *inst)
+{
+
+	dev_dbg(inst->dev, "Initialising SMI registers...");
+	/* Disable the peripheral if already enabled */
+	write_smi_reg(inst, 0, SMICS);
+	write_smi_reg(inst, 0, SMIDCS);
+
+	smi_get_default_settings(inst);
+	bcm2835_smi_set_regs_from_settings(inst);
+	smi_set_address(inst, 0);
+
+	write_smi_reg(inst, read_smi_reg(inst, SMICS) | SMICS_ENABLE, SMICS);
+	write_smi_reg(inst, read_smi_reg(inst, SMIDCS) | SMIDCS_ENABLE,
+		SMIDCS);
+}
+
+/****************************************************************************
+*
+*   Low-level SMI access functions
+*   Other modules should use the exported higher-level functions e.g.
+*   bcm2835_smi_write_buf() unless they have a good reason to use these
+*
+***************************************************************************/
+
+static inline uint32_t smi_read_single_word(struct bcm2835_smi_instance *inst)
+{
+	int timeout = 0;
+
+	write_smi_reg(inst, SMIDCS_ENABLE, SMIDCS);
+	write_smi_reg(inst, SMIDCS_ENABLE | SMIDCS_START, SMIDCS);
+	/* Make sure things happen in the right order...*/
+	mb();
+	while (!(read_smi_reg(inst, SMIDCS) & SMIDCS_DONE) &&
+		++timeout < 10000)
+		;
+	if (timeout < 10000)
+		return read_smi_reg(inst, SMIDD);
+
+	dev_err(inst->dev,
+		"SMI direct read timed out (is the clock set up correctly?)");
+	return 0;
+}
+
+static inline void smi_write_single_word(struct bcm2835_smi_instance *inst,
+	uint32_t data)
+{
+	int timeout = 0;
+
+	write_smi_reg(inst, SMIDCS_ENABLE | SMIDCS_WRITE, SMIDCS);
+	write_smi_reg(inst, data, SMIDD);
+	write_smi_reg(inst, SMIDCS_ENABLE | SMIDCS_WRITE | SMIDCS_START,
+		SMIDCS);
+
+	while (!(read_smi_reg(inst, SMIDCS) & SMIDCS_DONE) &&
+		++timeout < 10000)
+		;
+	if (timeout >= 10000)
+		dev_err(inst->dev,
+		"SMI direct write timed out (is the clock set up correctly?)");
+}
+
+/* Initiates a programmed read into the read FIFO. It is up to the caller to
+ * read data from the FIFO -  either via paced DMA transfer,
+ * or polling SMICS_RXD to check whether data is available.
+ * SMICS_ACTIVE will go low upon completion. */
+static void smi_init_programmed_read(struct bcm2835_smi_instance *inst,
+	int num_transfers)
+{
+	int smics_temp;
+
+	/* Disable the peripheral: */
+	smics_temp = read_smi_reg(inst, SMICS) & ~(SMICS_ENABLE | SMICS_WRITE);
+	write_smi_reg(inst, smics_temp, SMICS);
+	while (read_smi_reg(inst, SMICS) & SMICS_ENABLE)
+		;
+
+	/* Program the transfer count: */
+	write_smi_reg(inst, num_transfers, SMIL);
+
+	/* re-enable and start: */
+	smics_temp |= SMICS_ENABLE;
+	write_smi_reg(inst, smics_temp, SMICS);
+	smics_temp |= SMICS_CLEAR;
+	/* Just to be certain: */
+	mb();
+	while (read_smi_reg(inst, SMICS) & SMICS_ACTIVE)
+		;
+	write_smi_reg(inst, smics_temp, SMICS);
+	smics_temp |= SMICS_START;
+	write_smi_reg(inst, smics_temp, SMICS);
+}
+
+/* Initiates a programmed write sequence, using data from the write FIFO.
+ * It is up to the caller to initiate a DMA transfer before calling,
+ * or use another method to keep the write FIFO topped up.
+ * SMICS_ACTIVE will go low upon completion.
+ */
+static void smi_init_programmed_write(struct bcm2835_smi_instance *inst,
+	int num_transfers)
+{
+	int smics_temp;
+
+	/* Disable the peripheral: */
+	smics_temp = read_smi_reg(inst, SMICS) & ~SMICS_ENABLE;
+	write_smi_reg(inst, smics_temp, SMICS);
+	while (read_smi_reg(inst, SMICS) & SMICS_ENABLE)
+		;
+
+	/* Program the transfer count: */
+	write_smi_reg(inst, num_transfers, SMIL);
+
+	/* setup, re-enable and start: */
+	smics_temp |= SMICS_WRITE | SMICS_ENABLE;
+	write_smi_reg(inst, smics_temp, SMICS);
+	smics_temp |= SMICS_START;
+	write_smi_reg(inst, smics_temp, SMICS);
+}
+
+/* Initiate a read and then poll FIFO for data, reading out as it appears. */
+static void smi_read_fifo(struct bcm2835_smi_instance *inst,
+	uint32_t *dest, int n_bytes)
+{
+	if (read_smi_reg(inst, SMICS) & SMICS_RXD) {
+		smi_dump_context_labelled(inst,
+			"WARNING: read FIFO not empty at start of read call.");
+		while (read_smi_reg(inst, SMICS))
+			;
+	}
+
+	/* Dispatch the read: */
+	if (inst->settings.data_width == SMI_WIDTH_8BIT)
+		smi_init_programmed_read(inst, n_bytes);
+	else if (inst->settings.data_width == SMI_WIDTH_16BIT)
+		smi_init_programmed_read(inst, n_bytes / 2);
+	else {
+		dev_err(inst->dev, "Unsupported data width for read.");
+		return;
+	}
+
+	/* Poll FIFO to keep it empty */
+	while (!(read_smi_reg(inst, SMICS) & SMICS_DONE))
+		if (read_smi_reg(inst, SMICS) & SMICS_RXD)
+			*dest++ = read_smi_reg(inst, SMID);
+
+	/* Ensure that the FIFO is emptied */
+	if (read_smi_reg(inst, SMICS) & SMICS_RXD) {
+		int fifo_count;
+
+		fifo_count = GET_BIT_FIELD(read_smi_reg(inst, SMIFD),
+			SMIFD_FCNT);
+		while (fifo_count--)
+			*dest++ = read_smi_reg(inst, SMID);
+	}
+
+	if (!(read_smi_reg(inst, SMICS) & SMICS_DONE))
+		smi_dump_context_labelled(inst,
+			"WARNING: transaction finished but done bit not set.");
+
+	if (read_smi_reg(inst, SMICS) & SMICS_RXD)
+		smi_dump_context_labelled(inst,
+			"WARNING: read FIFO not empty at end of read call.");
+
+}
+
+/* Initiate a write, and then keep the FIFO topped up. */
+static void smi_write_fifo(struct bcm2835_smi_instance *inst,
+	uint32_t *src, int n_bytes)
+{
+	int i, timeout = 0;
+
+	/* Empty FIFOs if not already so */
+	if (!(read_smi_reg(inst, SMICS) & SMICS_TXE)) {
+		smi_dump_context_labelled(inst,
+		    "WARNING: write fifo not empty at start of write call.");
+		write_smi_reg(inst, read_smi_reg(inst, SMICS) | SMICS_CLEAR,
+			SMICS);
+	}
+
+	/* Initiate the transfer */
+	if (inst->settings.data_width == SMI_WIDTH_8BIT)
+		smi_init_programmed_write(inst, n_bytes);
+	else if (inst->settings.data_width == SMI_WIDTH_16BIT)
+		smi_init_programmed_write(inst, n_bytes / 2);
+	else {
+		dev_err(inst->dev, "Unsupported data width for write.");
+		return;
+	}
+	/* Fill the FIFO: */
+	for (i = 0; i < (n_bytes - 1) / 4 + 1; ++i) {
+		while (!(read_smi_reg(inst, SMICS) & SMICS_TXD))
+			;
+		write_smi_reg(inst, *src++, SMID);
+	}
+	/* Busy wait... */
+	while (!(read_smi_reg(inst, SMICS) & SMICS_DONE) && ++timeout <
+		1000000)
+		;
+	if (timeout >= 1000000)
+		smi_dump_context_labelled(inst,
+			"Timed out on write operation!");
+	if (!(read_smi_reg(inst, SMICS) & SMICS_TXE))
+		smi_dump_context_labelled(inst,
+			"WARNING: FIFO not empty at end of write operation.");
+}
+
+/****************************************************************************
+*
+*   SMI DMA operations
+*
+***************************************************************************/
+
+/* Disable SMI and put it into the correct direction before doing DMA setup.
+   Stops spurious DREQs during setup. Peripheral is re-enabled by init_*() */
+static void smi_disable(struct bcm2835_smi_instance *inst,
+	enum dma_transfer_direction direction)
+{
+	int smics_temp = read_smi_reg(inst, SMICS) & ~SMICS_ENABLE;
+
+	if (direction == DMA_DEV_TO_MEM)
+		smics_temp &= ~SMICS_WRITE;
+	else
+		smics_temp |= SMICS_WRITE;
+	write_smi_reg(inst, smics_temp, SMICS);
+	while (read_smi_reg(inst, SMICS) & SMICS_ACTIVE)
+		;
+}
+
+static struct scatterlist *smi_scatterlist_from_buffer(
+	struct bcm2835_smi_instance *inst,
+	dma_addr_t buf,
+	size_t len,
+	struct scatterlist *sg)
+{
+	sg_init_table(sg, 1);
+	sg_dma_address(sg) = buf;
+	sg_dma_len(sg) = len;
+	return sg;
+}
+
+static void smi_dma_callback_user_copy(void *param)
+{
+	/* Notify the bottom half that a chunk is ready for user copy */
+	struct bcm2835_smi_instance *inst =
+		(struct bcm2835_smi_instance *)param;
+
+	up(&inst->bounce.callback_sem);
+}
+
+/* Creates a descriptor, assigns the given callback, and submits the
+   descriptor to dmaengine. Does not block - can queue up multiple
+   descriptors and then wait for them all to complete.
+   sg_len is the number of control blocks, NOT the number of bytes.
+   dir can be DMA_MEM_TO_DEV or DMA_DEV_TO_MEM.
+   callback can be NULL - in this case it is not called. */
+static inline struct dma_async_tx_descriptor *smi_dma_submit_sgl(
+	struct bcm2835_smi_instance *inst,
+	struct scatterlist *sgl,
+	size_t sg_len,
+	enum dma_transfer_direction dir,
+	dma_async_tx_callback callback)
+{
+	struct dma_async_tx_descriptor *desc;
+
+	desc = dmaengine_prep_slave_sg(inst->dma_chan,
+				       sgl,
+				       sg_len,
+				       dir,
+				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK |
+				       DMA_PREP_FENCE);
+	if (!desc) {
+		dev_err(inst->dev, "read_sgl: dma slave preparation failed!");
+		write_smi_reg(inst, read_smi_reg(inst, SMICS) & ~SMICS_ACTIVE,
+			SMICS);
+		while (read_smi_reg(inst, SMICS) & SMICS_ACTIVE)
+			cpu_relax();
+		write_smi_reg(inst, read_smi_reg(inst, SMICS) | SMICS_ACTIVE,
+			SMICS);
+		return NULL;
+	}
+	desc->callback = callback;
+	desc->callback_param = inst;
+	if (dmaengine_submit(desc) < 0)
+		return NULL;
+	return desc;
+}
+
+/* NB this function blocks until the transfer is complete */
+static void
+smi_dma_read_sgl(struct bcm2835_smi_instance *inst,
+	struct scatterlist *sgl, size_t sg_len, size_t n_bytes)
+{
+	struct dma_async_tx_descriptor *desc;
+
+	/* Disable SMI and set to read before dispatching DMA - if SMI is in
+	 * write mode and TX fifo is empty, it will generate a DREQ which may
+	 * cause the read DMA to complete before the SMI read command is even
+	 * dispatched! We want to dispatch DMA before SMI read so that reading
+	 * is gapless, for logic analyser.
+	 */
+
+	smi_disable(inst, DMA_DEV_TO_MEM);
+
+	desc = smi_dma_submit_sgl(inst, sgl, sg_len, DMA_DEV_TO_MEM, NULL);
+	dma_async_issue_pending(inst->dma_chan);
+
+	if (inst->settings.data_width == SMI_WIDTH_8BIT)
+		smi_init_programmed_read(inst, n_bytes);
+	else
+		smi_init_programmed_read(inst, n_bytes / 2);
+
+	if (dma_wait_for_async_tx(desc) == DMA_ERROR)
+		smi_dump_context_labelled(inst, "DMA timeout!");
+}
+
+static void
+smi_dma_write_sgl(struct bcm2835_smi_instance *inst,
+	struct scatterlist *sgl, size_t sg_len, size_t n_bytes)
+{
+	struct dma_async_tx_descriptor *desc;
+
+	if (inst->settings.data_width == SMI_WIDTH_8BIT)
+		smi_init_programmed_write(inst, n_bytes);
+	else
+		smi_init_programmed_write(inst, n_bytes / 2);
+
+	desc = smi_dma_submit_sgl(inst, sgl, sg_len, DMA_MEM_TO_DEV, NULL);
+	dma_async_issue_pending(inst->dma_chan);
+
+	if (dma_wait_for_async_tx(desc) == DMA_ERROR)
+		smi_dump_context_labelled(inst, "DMA timeout!");
+	else
+		/* Wait for SMI to finish our writes */
+		while (!(read_smi_reg(inst, SMICS) & SMICS_DONE))
+			cpu_relax();
+}
+
+ssize_t bcm2835_smi_user_dma(
+	struct bcm2835_smi_instance *inst,
+	enum dma_transfer_direction dma_dir,
+	char __user *user_ptr, size_t count,
+	struct bcm2835_smi_bounce_info **bounce)
+{
+	int chunk_no = 0, chunk_size, count_left = count;
+	struct scatterlist *sgl;
+	void (*init_trans_func)(struct bcm2835_smi_instance *, int);
+
+	spin_lock(&inst->transaction_lock);
+
+	if (dma_dir == DMA_DEV_TO_MEM)
+		init_trans_func = smi_init_programmed_read;
+	else
+		init_trans_func = smi_init_programmed_write;
+
+	smi_disable(inst, dma_dir);
+
+	sema_init(&inst->bounce.callback_sem, 0);
+	if (bounce)
+		*bounce = &inst->bounce;
+	while (count_left) {
+		chunk_size = count_left > DMA_BOUNCE_BUFFER_SIZE ?
+			DMA_BOUNCE_BUFFER_SIZE : count_left;
+		if (chunk_size == DMA_BOUNCE_BUFFER_SIZE) {
+			sgl =
+			&inst->bounce.sgl[chunk_no % DMA_BOUNCE_BUFFER_COUNT];
+		} else {
+			sgl = smi_scatterlist_from_buffer(
+				inst,
+				inst->bounce.phys[
+					chunk_no % DMA_BOUNCE_BUFFER_COUNT],
+				chunk_size,
+				&inst->buffer_sgl);
+		}
+
+		if (!smi_dma_submit_sgl(inst, sgl, 1, dma_dir,
+			smi_dma_callback_user_copy
+		)) {
+			dev_err(inst->dev, "sgl submit failed");
+			count = 0;
+			goto out;
+		}
+		count_left -= chunk_size;
+		chunk_no++;
+	}
+	dma_async_issue_pending(inst->dma_chan);
+
+	if (inst->settings.data_width == SMI_WIDTH_8BIT)
+		init_trans_func(inst, count);
+	else if (inst->settings.data_width == SMI_WIDTH_16BIT)
+		init_trans_func(inst, count / 2);
+out:
+	spin_unlock(&inst->transaction_lock);
+	return count;
+}
+EXPORT_SYMBOL(bcm2835_smi_user_dma);
+
+
+/****************************************************************************
+*
+*   High level buffer transfer functions - for use by other drivers
+*
+***************************************************************************/
+
+/* Buffer must be physically contiguous - i.e. kmalloc, not vmalloc! */
+void bcm2835_smi_write_buf(
+	struct bcm2835_smi_instance *inst,
+	const void *buf, size_t n_bytes)
+{
+	int odd_bytes = n_bytes & 0x3;
+
+	n_bytes -= odd_bytes;
+
+	spin_lock(&inst->transaction_lock);
+
+	if (n_bytes > DMA_THRESHOLD_BYTES) {
+		dma_addr_t phy_addr = dma_map_single(
+			inst->dev,
+			(void *)buf,
+			n_bytes,
+			DMA_TO_DEVICE);
+		struct scatterlist *sgl =
+			smi_scatterlist_from_buffer(inst, phy_addr, n_bytes,
+				&inst->buffer_sgl);
+
+		if (!sgl) {
+			smi_dump_context_labelled(inst,
+			"Error: could not create scatterlist for write!");
+			goto out;
+		}
+		smi_dma_write_sgl(inst, sgl, 1, n_bytes);
+
+		dma_unmap_single
+			(inst->dev, phy_addr, n_bytes, DMA_TO_DEVICE);
+	} else if (n_bytes) {
+		smi_write_fifo(inst, (uint32_t *) buf, n_bytes);
+	}
+	buf += n_bytes;
+
+	if (inst->settings.data_width == SMI_WIDTH_8BIT) {
+		while (odd_bytes--)
+			smi_write_single_word(inst, *(uint8_t *) (buf++));
+	} else {
+		while (odd_bytes >= 2) {
+			smi_write_single_word(inst, *(uint16_t *)buf);
+			buf += 2;
+			odd_bytes -= 2;
+		}
+		if (odd_bytes) {
+			/* Reading an odd number of bytes on a 16 bit bus is
+			   a user bug. It's kinder to fail early and tell them
+			   than to e.g. transparently give them the bottom byte
+			   of a 16 bit transfer. */
+			dev_err(inst->dev,
+		"WARNING: odd number of bytes specified for wide transfer.");
+			dev_err(inst->dev,
+		"At least one byte dropped as a result.");
+			dump_stack();
+		}
+	}
+out:
+	spin_unlock(&inst->transaction_lock);
+}
+EXPORT_SYMBOL(bcm2835_smi_write_buf);
+
+void bcm2835_smi_read_buf(struct bcm2835_smi_instance *inst,
+	void *buf, size_t n_bytes)
+{
+
+	/* SMI is inherently 32-bit, which causes surprising amounts of mess
+	   for bytes % 4 != 0. Easiest to avoid this mess altogether
+	   by handling remainder separately. */
+	int odd_bytes = n_bytes & 0x3;
+
+	spin_lock(&inst->transaction_lock);
+	n_bytes -= odd_bytes;
+	if (n_bytes > DMA_THRESHOLD_BYTES) {
+		dma_addr_t phy_addr = dma_map_single(inst->dev,
+						     buf, n_bytes,
+						     DMA_FROM_DEVICE);
+		struct scatterlist *sgl = smi_scatterlist_from_buffer(
+			inst, phy_addr, n_bytes,
+			&inst->buffer_sgl);
+		if (!sgl) {
+			smi_dump_context_labelled(inst,
+			"Error: could not create scatterlist for read!");
+			goto out;
+		}
+		smi_dma_read_sgl(inst, sgl, 1, n_bytes);
+		dma_unmap_single(inst->dev, phy_addr, n_bytes, DMA_FROM_DEVICE);
+	} else if (n_bytes) {
+		smi_read_fifo(inst, (uint32_t *)buf, n_bytes);
+	}
+	buf += n_bytes;
+
+	if (inst->settings.data_width == SMI_WIDTH_8BIT) {
+		while (odd_bytes--)
+			*((uint8_t *) (buf++)) = smi_read_single_word(inst);
+	} else {
+		while (odd_bytes >= 2) {
+			*(uint16_t *) buf = smi_read_single_word(inst);
+			buf += 2;
+			odd_bytes -= 2;
+		}
+		if (odd_bytes) {
+			dev_err(inst->dev,
+		"WARNING: odd number of bytes specified for wide transfer.");
+			dev_err(inst->dev,
+		"At least one byte dropped as a result.");
+			dump_stack();
+		}
+	}
+out:
+	spin_unlock(&inst->transaction_lock);
+}
+EXPORT_SYMBOL(bcm2835_smi_read_buf);
+
+void bcm2835_smi_set_address(struct bcm2835_smi_instance *inst,
+	unsigned int address)
+{
+	spin_lock(&inst->transaction_lock);
+	smi_set_address(inst, address);
+	spin_unlock(&inst->transaction_lock);
+}
+EXPORT_SYMBOL(bcm2835_smi_set_address);
+
+struct bcm2835_smi_instance *bcm2835_smi_get(struct device_node *node)
+{
+	struct platform_device *pdev;
+
+	if (!node)
+		return NULL;
+
+	pdev = of_find_device_by_node(node);
+	if (!pdev)
+		return NULL;
+
+	return platform_get_drvdata(pdev);
+}
+EXPORT_SYMBOL(bcm2835_smi_get);
+
+/****************************************************************************
+*
+*   bcm2835_smi_probe - called when the driver is loaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_dma_setup(struct bcm2835_smi_instance *inst)
+{
+	int i, rv = 0;
+
+	inst->dma_chan = dma_request_slave_channel(inst->dev, "rx-tx");
+
+	inst->dma_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	inst->dma_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	inst->dma_config.src_addr = inst->smi_regs_busaddr + SMID;
+	inst->dma_config.dst_addr = inst->dma_config.src_addr;
+	/* Direction unimportant - always overridden by prep_slave_sg */
+	inst->dma_config.direction = DMA_DEV_TO_MEM;
+	dmaengine_slave_config(inst->dma_chan, &inst->dma_config);
+	/* Alloc and map bounce buffers */
+	for (i = 0; i < DMA_BOUNCE_BUFFER_COUNT; ++i) {
+		inst->bounce.buffer[i] =
+		dmam_alloc_coherent(inst->dev, DMA_BOUNCE_BUFFER_SIZE,
+				&inst->bounce.phys[i],
+				GFP_KERNEL);
+		if (!inst->bounce.buffer[i]) {
+			dev_err(inst->dev, "Could not allocate buffer!");
+			rv = -ENOMEM;
+			break;
+		}
+		smi_scatterlist_from_buffer(
+			inst,
+			inst->bounce.phys[i],
+			DMA_BOUNCE_BUFFER_SIZE,
+			&inst->bounce.sgl[i]
+		);
+	}
+
+	return rv;
+}
+
+static int bcm2835_smi_probe(struct platform_device *pdev)
+{
+	int err;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct resource *ioresource;
+	struct bcm2835_smi_instance *inst;
+	const __be32 *addr;
+
+	/* We require device tree support */
+	if (!node)
+		return -EINVAL;
+	/* Allocate buffers and instance data */
+	inst = devm_kzalloc(dev, sizeof(struct bcm2835_smi_instance),
+		GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	inst->dev = dev;
+	spin_lock_init(&inst->transaction_lock);
+
+	ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	inst->smi_regs_ptr = devm_ioremap_resource(dev, ioresource);
+	if (IS_ERR(inst->smi_regs_ptr)) {
+		err = PTR_ERR(inst->smi_regs_ptr);
+		goto err;
+	}
+	addr = of_get_address(node, 0, NULL, NULL);
+	inst->smi_regs_busaddr = be32_to_cpu(*addr);
+
+	err = bcm2835_smi_dma_setup(inst);
+	if (err)
+		goto err;
+
+	/* request clock */
+	inst->clk = devm_clk_get(dev, NULL);
+	if (!inst->clk)
+		goto err;
+	clk_prepare_enable(inst->clk);
+
+	/* Finally, do peripheral setup */
+	smi_setup_regs(inst);
+
+	platform_set_drvdata(pdev, inst);
+
+	dev_info(inst->dev, "initialised");
+
+	return 0;
+err:
+	kfree(inst);
+	return err;
+}
+
+/****************************************************************************
+*
+*   bcm2835_smi_remove - called when the driver is unloaded.
+*
+***************************************************************************/
+
+static int bcm2835_smi_remove(struct platform_device *pdev)
+{
+	struct bcm2835_smi_instance *inst = platform_get_drvdata(pdev);
+	struct device *dev = inst->dev;
+
+	dmaengine_terminate_all(inst->dma_chan);
+	dma_release_channel(inst->dma_chan);
+
+	clk_disable_unprepare(inst->clk);
+
+	dev_info(dev, "SMI device removed - OK");
+	return 0;
+}
+
+/****************************************************************************
+*
+*   Register the driver with device tree
+*
+***************************************************************************/
+
+static const struct of_device_id bcm2835_smi_of_match[] = {
+	{.compatible = "brcm,bcm2835-smi",},
+	{ /* sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, bcm2835_smi_of_match);
+
+static struct platform_driver bcm2835_smi_driver = {
+	.probe = bcm2835_smi_probe,
+	.remove = bcm2835_smi_remove,
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+		   .of_match_table = bcm2835_smi_of_match,
+		   },
+};
+
+module_platform_driver(bcm2835_smi_driver);
+
+MODULE_ALIAS("platform:smi-bcm2835");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Device driver for BCM2835's secondary memory interface");
+MODULE_AUTHOR("Luke Wren <luke@raspberrypi.org>");
--- /dev/null
+++ b/include/linux/broadcom/bcm2835_smi.h
@@ -0,0 +1,391 @@
+/**
+ * Declarations and definitions for Broadcom's Secondary Memory Interface
+ *
+ * Written by Luke Wren <luke@raspberrypi.org>
+ * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
+ * Copyright (c) 2010-2012 Broadcom. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2, as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef BCM2835_SMI_H
+#define BCM2835_SMI_H
+
+#include <linux/ioctl.h>
+
+#ifndef __KERNEL__
+#include <stdint.h>
+#include <stdbool.h>
+#endif
+
+#define BCM2835_SMI_IOC_MAGIC 0x1
+#define BCM2835_SMI_INVALID_HANDLE (~0)
+
+/* IOCTLs 0x100...0x1ff are not device-specific - we can use them */
+#define BCM2835_SMI_IOC_GET_SETTINGS    _IO(BCM2835_SMI_IOC_MAGIC, 0)
+#define BCM2835_SMI_IOC_WRITE_SETTINGS  _IO(BCM2835_SMI_IOC_MAGIC, 1)
+#define BCM2835_SMI_IOC_ADDRESS	 _IO(BCM2835_SMI_IOC_MAGIC, 2)
+#define BCM2835_SMI_IOC_MAX	     2
+
+#define SMI_WIDTH_8BIT 0
+#define SMI_WIDTH_16BIT 1
+#define SMI_WIDTH_9BIT 2
+#define SMI_WIDTH_18BIT 3
+
+/* max number of bytes where DMA will not be used */
+#define DMA_THRESHOLD_BYTES 128
+#define DMA_BOUNCE_BUFFER_SIZE (1024 * 1024 / 2)
+#define DMA_BOUNCE_BUFFER_COUNT 3
+
+
+struct smi_settings {
+	int data_width;
+	/* Whether or not to pack multiple SMI transfers into a
+	   single 32 bit FIFO word */
+	bool pack_data;
+
+	/* Timing for reads (writes the same but for WE)
+	 *
+	 * OE ----------+	   +--------------------
+	 *		|	   |
+	 *		+----------+
+	 * SD -<==============================>-----------
+	 * SA -<=========================================>-
+	 *    <-setup->  <-strobe ->  <-hold ->  <- pace ->
+	 */
+
+	int read_setup_time;
+	int read_hold_time;
+	int read_pace_time;
+	int read_strobe_time;
+
+	int write_setup_time;
+	int write_hold_time;
+	int write_pace_time;
+	int write_strobe_time;
+
+	bool dma_enable;		/* DREQs */
+	bool dma_passthrough_enable;	/* External DREQs */
+	int dma_read_thresh;
+	int dma_write_thresh;
+	int dma_panic_read_thresh;
+	int dma_panic_write_thresh;
+};
+
+/****************************************************************************
+*
+*   Declare exported SMI functions
+*
+***************************************************************************/
+
+#ifdef __KERNEL__
+
+#include <linux/dmaengine.h> /* for enum dma_transfer_direction */
+#include <linux/of.h>
+#include <linux/semaphore.h>
+
+struct bcm2835_smi_instance;
+
+struct bcm2835_smi_bounce_info {
+	struct semaphore callback_sem;
+	void *buffer[DMA_BOUNCE_BUFFER_COUNT];
+	dma_addr_t phys[DMA_BOUNCE_BUFFER_COUNT];
+	struct scatterlist sgl[DMA_BOUNCE_BUFFER_COUNT];
+};
+
+
+void bcm2835_smi_set_regs_from_settings(struct bcm2835_smi_instance *);
+
+struct smi_settings *bcm2835_smi_get_settings_from_regs(
+	struct bcm2835_smi_instance *inst);
+
+void bcm2835_smi_write_buf(
+	struct bcm2835_smi_instance *inst,
+	const void *buf,
+	size_t n_bytes);
+
+void bcm2835_smi_read_buf(
+	struct bcm2835_smi_instance *inst,
+	void *buf,
+	size_t n_bytes);
+
+void bcm2835_smi_set_address(struct bcm2835_smi_instance *inst,
+	unsigned int address);
+
+ssize_t bcm2835_smi_user_dma(
+	struct bcm2835_smi_instance *inst,
+	enum dma_transfer_direction dma_dir,
+	char __user *user_ptr,
+	size_t count,
+	struct bcm2835_smi_bounce_info **bounce);
+
+struct bcm2835_smi_instance *bcm2835_smi_get(struct device_node *node);
+
+#endif /* __KERNEL__ */
+
+/****************************************************************
+*
+*	Implementation-only declarations
+*
+****************************************************************/
+
+#ifdef BCM2835_SMI_IMPLEMENTATION
+
+/* Clock manager registers for SMI clock: */
+#define CM_SMI_BASE_ADDRESS ((BCM2708_PERI_BASE) + 0x1010b0)
+/* Clock manager "password" to protect registers from spurious writes */
+#define CM_PWD (0x5a << 24)
+
+#define CM_SMI_CTL	0x00
+#define CM_SMI_DIV	0x04
+
+#define CM_SMI_CTL_FLIP (1 << 8)
+#define CM_SMI_CTL_BUSY (1 << 7)
+#define CM_SMI_CTL_KILL (1 << 5)
+#define CM_SMI_CTL_ENAB (1 << 4)
+#define CM_SMI_CTL_SRC_MASK (0xf)
+#define CM_SMI_CTL_SRC_OFFS (0)
+
+#define CM_SMI_DIV_DIVI_MASK (0xf <<  12)
+#define CM_SMI_DIV_DIVI_OFFS (12)
+#define CM_SMI_DIV_DIVF_MASK (0xff << 4)
+#define CM_SMI_DIV_DIVF_OFFS (4)
+
+/* SMI register mapping:*/
+#define SMI_BASE_ADDRESS ((BCM2708_PERI_BASE) + 0x600000)
+
+#define SMICS	0x00	/* control + status register		*/
+#define SMIL	0x04	/* length/count (n external txfers)	*/
+#define SMIA	0x08	/* address register			*/
+#define SMID	0x0c	/* data register			*/
+#define SMIDSR0	0x10	/* device 0 read settings		*/
+#define SMIDSW0	0x14	/* device 0 write settings		*/
+#define SMIDSR1	0x18	/* device 1 read settings		*/
+#define SMIDSW1	0x1c	/* device 1 write settings		*/
+#define SMIDSR2	0x20	/* device 2 read settings		*/
+#define SMIDSW2	0x24	/* device 2 write settings		*/
+#define SMIDSR3	0x28	/* device 3 read settings		*/
+#define SMIDSW3	0x2c	/* device 3 write settings		*/
+#define SMIDC	0x30	/* DMA control registers		*/
+#define SMIDCS	0x34	/* direct control/status register	*/
+#define SMIDA	0x38	/* direct address register		*/
+#define SMIDD	0x3c	/* direct data registers		*/
+#define SMIFD	0x40	/* FIFO debug register			*/
+
+
+
+/* Control and Status register bits:
+ * SMICS_RXF	: RX fifo full: 1 when RX fifo is full
+ * SMICS_TXE	: TX fifo empty: 1 when empty.
+ * SMICS_RXD	: RX fifo contains data: 1 when there is data.
+ * SMICS_TXD	: TX fifo can accept data: 1 when true.
+ * SMICS_RXR	: RX fifo needs reading: 1 when fifo more than 3/4 full, or
+ *		  when "DONE" and fifo not emptied.
+ * SMICS_TXW	: TX fifo needs writing: 1 when less than 1/4 full.
+ * SMICS_AFERR	: AXI FIFO error: 1 when fifo read when empty or written
+ *		  when full. Write 1 to clear.
+ * SMICS_EDREQ	: 1 when external DREQ received.
+ * SMICS_PXLDAT	:  Pixel data:	write 1 to enable pixel transfer modes.
+ * SMICS_SETERR	: 1 if there was an error writing to setup regs (e.g.
+ *		  tx was in progress). Write 1 to clear.
+ * SMICS_PVMODE	: Set to 1 to enable pixel valve mode.
+ * SMICS_INTR	: Set to 1 to enable interrupt on RX.
+ * SMICS_INTT	: Set to 1 to enable interrupt on TX.
+ * SMICS_INTD	: Set to 1 to enable interrupt on DONE condition.
+ * SMICS_TEEN	: Tear effect mode enabled: Programmed transfers will wait
+ *		  for a TE trigger before writing.
+ * SMICS_PAD1	: Padding settings for external transfers. For writes: the
+ *		  number of bytes initially written to  the TX fifo that
+ * SMICS_PAD0	: should be ignored. For reads: the number of bytes that will
+ *		  be read before the data, and should be dropped.
+ * SMICS_WRITE	: Transfer direction: 1 = write to external device, 0 = read
+ * SMICS_CLEAR	: Write 1 to clear the FIFOs.
+ * SMICS_START	: Write 1 to start the programmed transfer.
+ * SMICS_ACTIVE	: Reads as 1 when a programmed transfer is underway.
+ * SMICS_DONE	: Reads as 1 when transfer finished. For RX, not set until
+ *		  FIFO emptied.
+ * SMICS_ENABLE	: Set to 1 to enable the SMI peripheral, 0 to disable.
+ */
+
+#define SMICS_RXF	(1 << 31)
+#define SMICS_TXE	(1 << 30)
+#define SMICS_RXD	(1 << 29)
+#define SMICS_TXD	(1 << 28)
+#define SMICS_RXR	(1 << 27)
+#define SMICS_TXW	(1 << 26)
+#define SMICS_AFERR	(1 << 25)
+#define SMICS_EDREQ	(1 << 15)
+#define SMICS_PXLDAT	(1 << 14)
+#define SMICS_SETERR	(1 << 13)
+#define SMICS_PVMODE	(1 << 12)
+#define SMICS_INTR	(1 << 11)
+#define SMICS_INTT	(1 << 10)
+#define SMICS_INTD	(1 << 9)
+#define SMICS_TEEN	(1 << 8)
+#define SMICS_PAD1	(1 << 7)
+#define SMICS_PAD0	(1 << 6)
+#define SMICS_WRITE	(1 << 5)
+#define SMICS_CLEAR	(1 << 4)
+#define SMICS_START	(1 << 3)
+#define SMICS_ACTIVE	(1 << 2)
+#define SMICS_DONE	(1 << 1)
+#define SMICS_ENABLE	(1 << 0)
+
+/* Address register bits: */
+
+#define SMIA_DEVICE_MASK ((1 << 9) | (1 << 8))
+#define SMIA_DEVICE_OFFS (8)
+#define SMIA_ADDR_MASK (0x3f)	/* bits 5 -> 0 */
+#define SMIA_ADDR_OFFS (0)
+
+/* DMA control register bits:
+ * SMIDC_DMAEN	: DMA enable: set 1: DMA requests will be issued.
+ * SMIDC_DMAP	: DMA passthrough: when set to 0, top two data pins are used by
+ *		  SMI as usual. When set to 1, the top two pins are used for
+ *		  external DREQs: pin 16 read request, 17 write.
+ * SMIDC_PANIC*	: Threshold at which DMA will panic during read/write.
+ * SMIDC_REQ*	: Threshold at which DMA will generate a DREQ.
+ */
+
+#define SMIDC_DMAEN		(1 << 28)
+#define SMIDC_DMAP		(1 << 24)
+#define SMIDC_PANICR_MASK	(0x3f << 18)
+#define SMIDC_PANICR_OFFS	(18)
+#define SMIDC_PANICW_MASK	(0x3f << 12)
+#define SMIDC_PANICW_OFFS	(12)
+#define SMIDC_REQR_MASK		(0x3f << 6)
+#define SMIDC_REQR_OFFS		(6)
+#define SMIDC_REQW_MASK		(0x3f)
+#define SMIDC_REQW_OFFS		(0)
+
+/* Device settings register bits: same for all 4 (or 3?) device register sets.
+ * Device read settings:
+ * SMIDSR_RWIDTH	: Read transfer width. 00 = 8bit, 01 = 16bit,
+ *			  10 = 18bit, 11 = 9bit.
+ * SMIDSR_RSETUP	: Read setup time: number of core cycles between chip
+ *			  select/address and read strobe. Min 1, max 64.
+ * SMIDSR_MODE68	: 1 for System 68 mode (i.e. enable + direction pins,
+ *			  rather than OE + WE pin)
+ * SMIDSR_FSETUP	: If set to 1, setup time only applies to first
+ *			  transfer after address change.
+ * SMIDSR_RHOLD		: Number of core cycles between read strobe going
+ *			  inactive and CS/address going inactive. Min 1, max 64
+ * SMIDSR_RPACEALL	: When set to 1, this device's RPACE value will always
+ *			  be used for the next transaction, even if it is not
+ *			  to this device.
+ * SMIDSR_RPACE		: Number of core cycles spent waiting between CS
+ *			  deassert and start of next transfer. Min 1, max 128
+ * SMIDSR_RDREQ		: 1 = use external DMA request on SD16 to pace reads
+ *			  from device. Must also set DMAP in SMICS.
+ * SMIDSR_RSTROBE	: Number of cycles to assert the read strobe.
+ *			  min 1, max 128.
+ */
+#define SMIDSR_RWIDTH_MASK	((1<<31)|(1<<30))
+#define SMIDSR_RWIDTH_OFFS	(30)
+#define SMIDSR_RSETUP_MASK	(0x3f << 24)
+#define SMIDSR_RSETUP_OFFS	(24)
+#define SMIDSR_MODE68		(1 << 23)
+#define SMIDSR_FSETUP		(1 << 22)
+#define SMIDSR_RHOLD_MASK	(0x3f << 16)
+#define SMIDSR_RHOLD_OFFS	(16)
+#define SMIDSR_RPACEALL		(1 << 15)
+#define SMIDSR_RPACE_MASK	(0x7f << 8)
+#define SMIDSR_RPACE_OFFS	(8)
+#define SMIDSR_RDREQ		(1 << 7)
+#define SMIDSR_RSTROBE_MASK	(0x7f)
+#define SMIDSR_RSTROBE_OFFS	(0)
+
+/* Device write settings:
+ * SMIDSW_WWIDTH	: Write transfer width. 00 = 8bit, 01 = 16bit,
+ *			  10= 18bit, 11 = 9bit.
+ * SMIDSW_WSETUP	: Number of cycles between CS assert and write strobe.
+ *			  Min 1, max 64.
+ * SMIDSW_WFORMAT	: Pixel format of input. 0 = 16bit RGB 565,
+ *			  1 = 32bit RGBA 8888
+ * SMIDSW_WSWAP		: 1 = swap pixel data bits. (Use with SMICS_PXLDAT)
+ * SMIDSW_WHOLD		: Time between WE deassert and CS deassert. 1 to 64
+ * SMIDSW_WPACEALL	: 1: this device's WPACE will be used for the next
+ *			  transfer, regardless of that transfer's device.
+ * SMIDSW_WPACE		: Cycles between CS deassert and next CS assert.
+ *			  Min 1, max 128
+ * SMIDSW_WDREQ		: Use external DREQ on pin 17 to pace writes. DMAP must
+ *			  be set in SMICS.
+ * SMIDSW_WSTROBE	: Number of cycles to assert the write strobe.
+ *			  Min 1, max 128
+ */
+#define SMIDSW_WWIDTH_MASK	 ((1<<31)|(1<<30))
+#define SMIDSW_WWIDTH_OFFS	(30)
+#define SMIDSW_WSETUP_MASK	(0x3f << 24)
+#define SMIDSW_WSETUP_OFFS	(24)
+#define SMIDSW_WFORMAT		(1 << 23)
+#define SMIDSW_WSWAP		(1 << 22)
+#define SMIDSW_WHOLD_MASK	(0x3f << 16)
+#define SMIDSW_WHOLD_OFFS	(16)
+#define SMIDSW_WPACEALL		(1 << 15)
+#define SMIDSW_WPACE_MASK	(0x7f << 8)
+#define SMIDSW_WPACE_OFFS	(8)
+#define SMIDSW_WDREQ		(1 << 7)
+#define SMIDSW_WSTROBE_MASK	 (0x7f)
+#define SMIDSW_WSTROBE_OFFS	 (0)
+
+/* Direct transfer control + status register
+ * SMIDCS_WRITE	: Direction of transfer: 1 -> write, 0 -> read
+ * SMIDCS_DONE	: 1 when a transfer has finished. Write 1 to clear.
+ * SMIDCS_START	: Write 1 to start a transfer, if one is not already underway.
+ * SMIDCE_ENABLE: Write 1 to enable SMI in direct mode.
+ */
+
+#define SMIDCS_WRITE		(1 << 3)
+#define SMIDCS_DONE		(1 << 2)
+#define SMIDCS_START		(1 << 1)
+#define SMIDCS_ENABLE		(1 << 0)
+
+/* Direct transfer address register
+ * SMIDA_DEVICE	: Indicates which of the device settings banks should be used.
+ * SMIDA_ADDR	: The value to be asserted on the address pins.
+ */
+
+#define SMIDA_DEVICE_MASK	((1<<9)|(1<<8))
+#define SMIDA_DEVICE_OFFS	(8)
+#define SMIDA_ADDR_MASK		(0x3f)
+#define SMIDA_ADDR_OFFS		(0)
+
+/* FIFO debug register
+ * SMIFD_FLVL	: The high-tide mark of FIFO count during the most recent txfer
+ * SMIFD_FCNT	: The current FIFO count.
+ */
+#define SMIFD_FLVL_MASK		(0x3f << 8)
+#define SMIFD_FLVL_OFFS		(8)
+#define SMIFD_FCNT_MASK		(0x3f)
+#define SMIFD_FCNT_OFFS		(0)
+
+#endif /* BCM2835_SMI_IMPLEMENTATION */
+
+#endif /* BCM2835_SMI_H */
